Hot top



"swan-WWW". 7

Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE LEELiQE -A IQJ BTE,or rrrrsnunen, AND EIJ IER B. WELCH, or McKEESPOBT,

PENNSYLVANIA, AssIeNons T FIRTH-STERLING STEEL COMPANY, or IIcxEEsroar,PENNSYLVANIA, A conronA'rIoN or PENNSYLVANIA HOT TOP Io Drawing.

This invention relates generally to hot grips commonly used in pouringsteel ingots. ot tops are refractory forms placed on the top of theingots and into which the metal is poured in order to maintain the topportion of the ingot in a molten condition so as to prevent or decreasethe formation of shrlnks and pipes in the ingot.

Up to the present time, these hot tops have 10 been made 0 clay or othersimilar refractory material. Clay hot tops do, to a certain extent,decrease the amount of shrinks and pipes in an ingot, but they are notof sufiiciently good insulating characteristics to prove satisfactory insome cases where itis desired to substantially eliminate entirely anyshrinks or pipes in the ingot. Furthermore, clay hot tops are relativelyexpensive. In using clay hot tops it is necessary to heat go them beforeapplying them to the ingot molds. Even when the hot tops are heatedbefore placing them on the ingot molds, they sometimes cool to such anextent before the I metal is poured into the mold that shrinks or pipesform.

In accordance with our invention, we provide hot tops which have a muchgreater insulating value than those heretofore employed. Accordingly, itis not necessary to 30 preheat our hot tops before applying them to themold. They have an insulating value sufiiciently great so as tomaterially decrease the amount of shrinks and pipes that wouldordinarily be formed in an ingot, and are 5 mainly composed of materialwhich is much cheaper than cla We take a car onaceous material ormixture of carbonaceous materials, such assay jggt, wood shavins,charcoal, coke, u 1 le q! ,SllCh as corn ggbs, corn stalks, sfil ayy, orm, and

mix this with JET ctor inder. The mixture is then formed into t edesired shape and dried.

If desired, instead of using the carbonaceous material and the binderalone, we can first coat the carbonaceous material with a I n such, forexample, as sodium chloride, sodium tungstate, or

This may be accomplished by immersing the Application filed September24, 1929. Serial No. 394,920.

sawdust or other carbonaceous material in a solution of thefire-proofing salt, and thereafter evaporating the water. This depositsa coating of a fire-proofing salt on the particles of the sawdust. Thesaw .isthen mixed with a biggie refera y a silica suc imhi n ilicate orpotassium s1 icate, and the mixture is then pressed into the desiredshape. The article so formed is dried in order to eliminate any excesswater which, on if present, might tend to cause the hot top todisintegrate when subjected to heat.

After the hot top has been dried it preferably is coated with a coatingof a silicate cement, such for example, as sodium silicate. .5 Thiscoating may be accomplished by dilpping the article or by painting itwith t e coating material or by any other desired method. The coatingprevents the article from absorbing moisture and also tends to 7 morefirml bind together any loose particles which mig t have resulted fromthe forming operation and prevents these loose particles from burningout when the hot top is used.

As a specific example of the manner of carrying out our invention,sawdust is first dried and then immersed in a solution of sodiumchloride. It is then heated to drive 011' the water and deposit a layerof sodium chloride on the particles which acts as a firea0 proofingmedium. The dried coated particles are then mixed with sodium silicatein such proportion as to cause the particles to adhere to each otherwhen they are pressed to shape. In practice we have found 6 a b volumeof oium toa ut ten arts lume of sawdust makes the mixture of aconsistency which can be satis- 1 ma mamas,

ac ory cement, with the saw V fifoofzid s aw dhst and binder In order toprevent the hot top from smouldering too greatly. The proportions ofsawdust to clay or other refractory material may "be varied to suit theconditions. We prefer to employ not less thanpercentsawdust Taninot'morg than iiftyp ercent clay. H For many'ffifrfioses a mixturea'fioiit'eighty percent sawdust and, percent cla has proved verysatisfactory. If cla or t er, refractory material is mixed wit thesawdust, a fire-proofing material such as sodium 5 chloride, sodiumtungstate, or alum, may or may not be used.

In the description we have referred to sawdust as being a carbonaceousmaterial suitable for making hot tops. It is to be 0 understood,however, that other carbonaceous materials having similar properties maybe used in place of sawdust.

Aside from the fact that hot tops may be made very cheaply according toour invention, our hot tops retain the heat much better than those nowin use and, accordingly, decrease the amount of shrinks and pipesordinarily present in ingots. We have referred specifically to thepouring of steel ingots,

but it should be understood that the hot tops may be used in pouringother metals.

We have described several preferred compositions and methods by whichour invention may be carried out, but it should be understood that theinvention may be otherwise embodied or practiced within the scope of thefollowing claims.

We claim:

1. A hot top comprising carbonaceous material, said carbonaceousmaterial being impregnated with a fire-proofing material, and a binder.

2. A hot top comprising carbonaceous material, said carbonaceousmaterial being impregnated with a fire-proofing material, a refractory,and a binder.

3. A hot top comprising carbonaceous material, a fire-proofing salt, anda silicate o binder.

4. A hot top comprising carbonaceous matg ial, sgdium chloride, and s odiumsilicate.

5. A hot top comprising carbonaceous ma- 6: terial, sodium chloride,clay, and sodium sili- "cafe.

our hands.

L. GERALD FIRTH. ELMER B. WELCH.

